3.1. Waste edible oil (WEO): availability, economic value and properties
The amount of WEO generated from every country worldwide is huge and varies accordingly to the amount of edible oil consumed. Annually, a total of more than 15 million tons of WEO is generated from selected countries in the world as shown in Table 5. It should be noted that the worldwide WEO is way much larger than that value. Therefore, WEO is readily available feedstock that can be used for biodiesel production. The cost for WEO is generally lower than fresh edible oil as a major fraction contributing to the cost lies in the collection and purifying processes. For comparison purposes, the costs of soybean and WEO are given. Currently, WEO from soybean is sold as yellow grease that has a market value of approximately $1.09/US gallon and is expected to rise to $1.21/US gallon by the year 2013. On the other hand, the price of soybean in the market is about $2.22/US gallon in year 2004 and is expected to rise to $2.47/US gallon in 2013 [45].